# coding: utf-8
import numpy as np
import matplotlib.pylab as plt
from mpl_toolkits.mplot3d import Axes3D

fig = plt.figure()
ax = Axes3D(fig)
# 2.X,Y value
X = np.arange(-4, 4, 0.25)
Y = np.arange(-4, 4, 0.25)

X, Y = np.meshgrid(X, Y)

Z = X**2 + Y**2

ax.plot_surface(X, Y, Z, rstride=1, cstride=1, cmap=plt.get_cmap('rainbow'))
ax.contourf(X, Y, Z, zdir='z', offset=-2, cmap='rainbow')

plt.savefig('draw.png')
